Rohini Nilekani (India)

55, FOUNDER, ARGHYAMSold $27 million worth of shares in Infosys last August and is donating some of the money to causes such as improving the quality of the country’s laws and preserving biodiversity. Also plans to donate $1.7 million to India’s oldest think tank, the New Delhi-based National Council of Applied Economic Research. (Husband NandanNilekani, an Infosys cofounder who lost a race for parliament this year, has donated $5.8 million to the organization.) She’s given away roughly $40 million over the years, with most going to Arghyam, which supports projects to protect groundwater and improve sanitation. She started the Bangalore nonprofit in 2001.